U.S. patent number 4,421,030 [Application Number 06/311,907] was granted by the patent office on 1983-12-20 for in-line fuze concept for antiarmor tactical warheads.
This patent grant is currently assigned to The Boeing Company. Invention is credited to Jon G. DeKoker.
United States Patent |
4,421,030 |
DeKoker |
December 20, 1983 |
In-line fuze concept for antiarmor tactical warheads
Abstract
An electronic safe and arm device for generating a trigger
signal for initiating detonation of a flying plate detonator. A
toroidal trigger capacitor surrounds the electronics of the device
and will be shorted to disable the safe and arm device if damage
occurs thereto. First and second sensor switches responsive to
selected flight parameters control the charging of the trigger
capacitor. A normally closed arm enable switch prevents the
charging of the trigger capacitor until after break-wire launch has
occurred.
Inventors: |
DeKoker; Jon G. (Renton,
WA) |
Assignee: |
The Boeing Company (Seattle,
WA)
|
Family
ID: |
23209016 |
Appl.
No.: |
06/311,907 |
Filed: |
October 15, 1981 |
Current U.S.
Class: |
102/218; 102/204;
102/206; 102/476 |
Current CPC
Class: |
F42C
11/00 (20130101) |
Current International
Class: |
F42C
11/00 (20060101); F42C 015/40 (); F42C 019/00 ();
F42B 013/10 () |
Field of
Search: |
;102/218,219,220,216,206,204,476 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Jordan; Charles T.
Attorney, Agent or Firm: Finnegan, Henderson, Farabow,
Garrett & Dunner
Claims
I claim:
1. A safe and arm device for supplying a triggering signal to an
explosive detonator of a shaped charge warhead flown to impact a
target comprising:
a power source;
a toroidally-shaped trigger capacitor surrounding a portion of said
shaped charge;
means for selectively coupling said power source to said trigger
capacitor to charge said trigger capacitor; and
means responsive to the impact of the warhead against the target
for enabling the discharge of said capacitor to generate said
triggering signal.
2. A safe and arm device according to claim 1 further including
means responsive to the flight of said warhead for enabling said
coupling means to supply said power from said power source to said
trigger capacitor.
3. A safe and arm device according to claim 2 wherein said coupling
means, said discharge enabling means, and said coupling enabling
means are surrounded by said toroidally shaped trigger capacitor
such that damage to said trigger capacitor will prevent the
charging thereof by said coupling means and said coupling enabling
means.
4. A safe and arm device according to claim 3 wherein said coupling
means comprises a DC-DC transverter connected between said power
source and said trigger capacitor.
5. A safe and arm device according to claim 2 or 4 wherein said
coupling enabling means further includes a normally open first
coupling switch and a first controlling sensor, said first
controlling sensor for closing said first coupling switch
responsive to said warhead's obtaining a predetermined acceleration
level.
6. A safe and arm device according to claim 5 wherein said warhead
is adapted to include a nose cap ejected a predetermined distance
from the launch of said warhead and wherein said coupling enabling
means includes a normally open second coupling switch and a second
controlling sensor, said second controlling sensor for closing said
second coupling switch responsive to the ejection of said nose
cap.
7. A safe and arm device according to claim 6 wherein said coupling
enabling means further includes an arm enable switch and means for
actuating said arm enable switch responsive to the launching of
said warhead.
8. A safe and arm device according to claim 1 wherein the explosive
detonator comprises a flying plate detonator.
9. A safe and arm device according to claim 6 further including a
bleeder resistor connected between said trigger capacitor and
ground for preventing the charging of said trigger capacitor when
either of said first coupling switch or said second coupling switch
is open.
10. A safe and arm device for supplying a triggering signal to an
explosive detonator of a warhead flown to impact a target
comprising:
a power source;
a trigger capacitor
means for selectively coupling said power source to said trigger
capacitor to charge said trigger capacitor; and
means responsive to the impact of the warhead against the target
for enabling the discharge of said trigger capacitor to generate
said triggering signal, said enabling means being surrounded by
said trigger capacitor such that damage to said trigger capacitor
will prevent the charging thereof by said coupling means.
11. A safe and arm device for supplying a trigger signal to an
explosive detonator in a warhead flown to impact a target
comprising:
a power source;
a trigger capacitor;
a DC-DC transverter for receiving power from said power source and
for generating a signal for charging said trigger capacitor;
a first normally open switch and a second normally open switch,
said first and second normally open switches being connected in
series between said power source and said DC-DC transverter;
a first sensor for closing said first switch responsive to a first
condition of said warhead;
a second sensor for closing said second switch responsive to a
second condition of said warhead; and
detonation switch means responsive to the impact of said warhead
against said target for enabling the discharge of said trigger
capacitor to generate said trigger signal.
Description
FIELD OF THE INVENTION
This invention relates with particularity to an inert safe and arm
device for supplying a trigger signal to a detonator in a
warhead.
BACKGROUND OF THE INVENTION
Hot wire detonators in existing tactical warhead safe and arm
devices explode readily if exposed to high temperatures, shock,
static discharges, or electromagnetic interference induced
currents. For this reason, military standards require that safe and
arm designs have a physical barrier between the detonator and the
warhead explosive to provide safety in the event of premature
detonator firing. This barrier must be mechanically removed during
the warhead arming sequence. Mechanical failure is common, and
packaging flexibility within the warhead is limited with the use of
mechanical safe and arm devices.
For shaped-charge antiarmor warheads employed in tactical
minimissiles such as WASP or the Assualt Breaker terminally guided
submissiles, the length required for mechanical safe and arm
devices is an appreciable percentage of the total length allocated
for ordnance. Also, it is common for such minimissiles to include
an infrared or millimeter wave seeker which further requires space
within the warhead. Thus, the actual amount of explosives carried
by the warhead is unduly limited and the resulting problem is
compounded by the fact that the warheads are required to defeat
increasingly resistant armored targets.
A partial solution to the problems arising from the use of
mechanical safe and arm devices is a safe and arm device which uses
a flying plate or slapper detonator. Such flying plate detonators
are known in the art and can initiate insensitive secondary
explosives such as hexanitrosostilbene (HNS) directly and,
therefore, do not require barriers in the explosive train. The
length required for such a flying plate detonator is only 0.040
inch (1 millimeter). An (HNS) explosive acceptor pellet is embedded
in the warhead explosive to provide a completely inert safe and arm
device in a manner that greatly simplifies the assembly, testing,
and logistical concerns associated with the warhead.
Flying plate detonators, as known in the art, require a firing
current of approximately 1500 amperes for a few microseconds. This
characteristic makes the safe and arm device immune to static
discharges and electromagnetic interference. Direct connection with
a 60 hz, 110 V or 220 V current or with 28 V DC missile battery
power will dud the detonator and will not initiate an explosion.
The HNS pellet is as insensitive to heat as the LX-14 explosive
commonly employed in a warhead. This type of explosive burns rather
than detonates if exposed to flame.
The flying plate detonator has not, however, provided a complete
solution to the need for a safe and arm device for tactical
missiles and warheads. This is because it is necessary to provide a
compact and reliable triggering circuit for initiating the
detonation of the flying plate detonator. Since there is no
mechanical barrier employed within the flying plate detonator, it
is extremely important that the triggering circuit not generate
transient or spurious signals capable of triggering the
detonator.
OBJECTS AND SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to trigger a
flying plate detonator in a reliable manner.
Another object of this invention is to prevent the triggering of a
flying plate or other safe and arm device in the event that damage
occurs to the triggering circuit.
Yet another object of this invention is to include all of the
components of a triggering circuit of a flying plate or other
detonator in a compact manner that will not decrease the amount of
room available in the warhead for explosives.
These and other objects are accomplished by a safe and arm device
for supplying a trigger signal to an explosive detonator in a
warhead flown to impact a target, comprising a power source, means
for selectively coupling the power source to the trigger capacitor
to charge the trigger capacitor, and means responsive to the impact
of the warhead against the target for enabling the discharge of the
trigger capacitor to generate the trigger signal.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings which are incorporated in and constitute
a part of the specification, illustrate an embodiment of the
invention and, together with the description, serve to explain the
principles of the invention.
FIG. 1 is a partial cross section of a warhead incorporating the
safe and arm triggering circuit of the instant invention.
FIGS. 2(a) and 2(b) illustrate the structure and operation of a
flying plate detonator usable with the safe and arm triggering
circuit of the instant invention.
FIG. 3 is a circuit diagram of the safe and arm triggering circuit
of the instant invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A partial cross section of a warhead 11 is illustrated in FIG. 1.
The warhead 11 includes a warhead casing 13 and a shaped charge
explosive 15. A copper liner 17 is provided on the interior surface
of the shaped charge 15.
A target impact sensor (not shown) is provided in the warhead 11 to
generate an impact signal at the time that the warhead 11 strikes
its assigned target or some other solid object. This impact signal
is supplied over an impact signal line 19 connected to a trigger
switch 21. The trigger switch 21 is connected to a detonator 23 and
to a high voltage trigger capacitor 25. The impact trigger switch
21 is normally an open circuit between the detonator 23 and the
trigger capacitor 25. Upon receiving an impact signal from the
impact signal line 19, the trigger switch 21 directly connects the
detonator 23 to the trigger capacitor 25 and permits the trigger
capacitor 25 to generate a trigger signal by discharging through
the detonator 23.
The warhead 11 further includes a circuit for charging the trigger
capacitor 25 under specified conditions. This circuit includes a
power source input 27 connected to a power source 51 (FIG. 3) and
to a first sensor switch 29. A second sensor switch 31 is connected
between the first sensor switch 29 and a DC-DC transverter 33. The
transverter 33, upon receiving power from the power source 51,
charges the trigger capacitor 25.
The first sensor switch 29 receives an input signal corresponding
to the jettisoning of the nose cap (not shown) covering the seeker
of the warhead 11. As known to one of ordinary skill in the art, it
is common for a warhead 11 to have a seeker for acquiring a target
and guiding the warhead thereto. During the launch of the warhead
11 and the initial portion of its flight, a nose cap covers and
protects the seeker. The nose cap is commonly jettisoned in
response to the warhead 11 obtaining a certain predetermined
acceleration.
The first sensor switch 29 is normally open to prevent current from
passing to the second sensor switch 31. However, upon receiving the
signal indicating the jettisoning of the warhead nose cap, the
first sensor switch 29 is closed.
The second sensor 31 switch is normally open and, therefore, will
interrupt the flow of current to the transverter 33 even when the
first sensor switch 29 is closed. The second sensor switch will
close upon the occurrence of a second condition of the warhead 11.
For example, the second sensor switch 31 may comprise a Rolamite
accelerometer which will close the contacts of switch 31 when the
proper launch acceleration magnitude and direction are sensed by
the inertial navigational system (not shown) included on board the
warhead 11. Such an accelerometer besides sensing the acceleration
of the warhead 11 is also electronically timed. The second sensor
switch 31 will not be closed if either the acceleration duration or
magnitude is below specified limits. Moreover, even if the
acceleration profile is acceptable, the second sensor switch 31
will not be closed until a specified time period has elapsed
corresponding to a safe separation distance of the warhead from its
associated carrier.
An arm enable switch 35 further interrupts the flow of current from
the power source 51 over the lead 27 to the first sensor switch 29.
The arm enable switch is normally closed and is opened only upon
the occurrence of a signal indicating the launch of the warhead 11.
Such an electrical signal may be triggered by a break-wire launch.
A break-wire launch, as is recognized by one skilled in the art,
requires warhead motor ignition, retraction of the warhead
retaining clamp, and initial motion of the warhead.
As illustrated in FIG. 1, the trigger capacitor 25 is toroidally
shaped and provided near the neck of the shaped charge 15.
Moreover, the detonator 23, first sensor switch 29, second sensor
switch 31, DC-DC transverter 33, and impact trigger switch 21 are
surrounded by the trigger capacitor 25. In case of fire or the
puncture of the safe and arm device, the trigger capacitor 25 will
fail in a short circuit mode before any other components of the
trigger circuit fail. Because a shorted capacitor cannot be
charged, the high currents (1500 amperes) required by the flying
plate detonator cannot be generated and the flying plate detonator
will remain inert.
FIG. 2(a) illustrates the components constituting a flying plate
detonator. These components include an HNS pellet 41 which is
embedded in the shape charged explosive 15. A cap 43 with a central
barrel is attached to one end of the HNS pellet 41. A thin plastic
flyer 45 overlies the top of the cap 43. A thin metal foil 47 is
attached to the flyer 45 and connected between the discharge side
of the trigger capacitor 25 and ground.
As shown in FIG. 2(b)(1) the application of the high current
trigger signal from the trigger capacitor 25 explosively vaporizes
the thin metal foil 47 in a fraction of a microsecond. The
resulting metal vapor shears the thin plastic flyer 45 (FIG.
2(b)(2)) and accelerates a portion of the flyer 45 down the barrel
of the cap 43. The barrel is approximately 1 mm in length. The
impact of a sheared portion of the flyer 45 (FIG. 2(b)(3)) and the
HNS pellet causes detonation thereof. The function time of the
trigger circuit and the flying plate detonator is a few
microseconds from receipt of the trigger signal to warhead
detonation.
FIG. 3 is a schematic illustration of the trigger circuit of the
instant invention. The power source 51 is connected to a means for
selectively coupling the power source 51 to the trigger capacitor
25 to charge the trigger capacitor. As embodied herein, the
coupling means comprises the DC-DC transverter 33 and means
responsive to the flight of the warhead for transferring power from
the power source 51 to the transverter 33. The transferring means
as embodied as the first sensor switch 29 and the second sensor
switch 31.
The first sensor switch 29 comprises a first controlling sensor 53
for opening and closing a first coupling switch 55. The second
sensor switch 31 comprises a second controlling sensor 57 for
opening and closing a second coupling switch 59. As stated above,
the first sensor switch responds to the jettisoning of the nose cap
covering the seeker on the warhead 11. A signal indicative of that
occurrence is supplied at terminal A of the first controlling
sensor 53. Upon receiving the nose cap jettison signal, the
controlling sensor 53 closes the first coupling switch 55.
The second controlling sensor 57 comprises the Rolamite
accelerometer described above. When the warhead 11 obtains a
predetermined launch acceleration magnitude and direction at a time
ensuring a safe separation distance from the warhead carrier, the
second controlling sensor 57 will close the second coupling switch
59.
It is only when the first and second coupling switches 55 and 59
are closed that the power from the power source 51 is supplied to
the transverter 33. However, the power will not be supplied to the
transverter 33 even if switches 55 and 59 are closed unless the arm
enable switch 35 is open. The arm enable switch is normally
grounded and is controlled by a command enable module 61. The
command enable module 61 responds to the above-described break wire
condition to cause arm enable switch 35 to open and enable power to
be supplied to transverter 33 when switches 55 and 59 are
closed.
The output of the transverter 33 is connected to charging resistor
63 which in turn is connected to bleeder resistor 65 and the
trigger capacitor 25. The trigger capacitor 25 is shunted to ground
by the bleeder resistor 65 to ensure that a voltage cannot be
maintained on the capacitor 25 in the absence of the power from the
power source 51.
The trigger circuit further includes means responsive to the impact
of the warhead against the target for enabling the discharge of the
trigger capacitor 25 to generate the triggering signal. As embodied
herein, the discharge enabling means comprises a fuse electronics
assembly 67 which performs the above-described function of
generating a signal at the time of warhead impact against a target.
This signal is supplied to a gate 69. In the absence of the impact
signal, the gate 69 constitutes an open circuit between the trigger
capacitor 25 and the coil 47 of the flying plate detonator. Upon
receiving the impact signal, however, the gate 69 enables the
trigger capacitor 25 to discharge though the coil 47 to initiate
detonation of the flying plate detonator.
A display and testing module 71 may be connected to the fuse
electronics assembly 67 during the manufacture of the warhead 11 to
perform selected test routines thereon. Moreover, the display and
test module may be connected to a terminal (not shown) of the
warhead following manufacture to enable confidence testing of the
fuse assembly.
It will be further apparent to those skilled in the art, that
modifications and variations can be made to the flying plate
detonator trigger circuit without departing from the scope or
spirit of the invention and it is intended that the present
invention cover the modifications and variations of the circuit
provided that they come within the scope of the appended claims and
their equivalents.
* * * * *